Good point about the CSS transforms. As for the resizing and style recalcs, I just did profiled a simple test case ( albeit with a 2D canvas ) and style recalcs only occured while resizing the window which is expected. No extra cost in this case.

Using CSS, the sizing and vertical centering should occur only in the compositer. As a rule of thumb, I try to touch CSS properties in JS as a last resort.

However this potential optimization is moot since the canvas is resized to match the viewport. The browsers most likely freak out and trigger a style recalc anyways. And to be completely honest, no one resizes the browser window for several seconds to see how smoothly, or not, a prod/app/demo is.